In organizations such as large offices, many stations, e.g. telephone sets, are connected to the public switched telephone network through a Local Exchange Carrier (LEC). A call originating at one of these stations is connected by the LEC to an outside line. For the convenience of outside callers, many such outside lines may share a single number. Other systems, such as Interactive Voice Response systems (IVR's) and Call Routers (hereinafter sometimes, collectively “call response systems”) also commonly have a number of outside lines sharing a single number. (IVR's are computers deigned to interact via Dual Tone Multi-Frequency (DTMF) and audio signals with both callers and called parties. Call Routers are a type of routing system that handles, or routes, calls to call centers such as those that handle catalogue sales.) Typically, thought not necessarily, such shared numbers are toll free “8xx” numbers. Many such systems are unable to receive a Network Call ID (identification) (NCID) or out-of-band signals and rely instead on the combination of the Automatic Number Identification (ANI), 8xx, to identify the call.
When a switch in the telephone network receives a call to an 8xx number it sends a routing query to a system comprising network components (i.e. software modules running on one or more network hardware systems) including: a Data Access Point (DAP) a Remote Data Gateway (RDG), a Router, and a Parking Manager (PM); and receives a response containing routing information. When the DAP receives the routing query it consults its database. For calls of the type which are to be processed in accordance with the present invention, the database query informs the DAP to forward the routing query to an RDG, which translates between the messaging protocols used by the DAP and protocols used by other network components. The DAP sends the routing query to a Router, which determines routing for the call in accordance with predetermined routing plans, or strategies, in a known manner. (Those skilled in the art will recognize that, despite the similarity in terminology, Routers and Call Routers are distinct devices, having different functions.) If the Router determines that the call should be parked, it sends a Park Request to a PM. The PM determines if and where the call should be parked in a known manner, and returns this information to the Router, which forwards it to the RDG, which reformats the information and forwards it to the DAP, which reformats the information again and sends it to the switch. As is known, at this point the DAP also performs a one-to-one mapping of the 8xx into a Dialed Number Identification System (DNIS) value and incorporates the DNIS value into the message to the switch. The switch then routes the call as provided in the message.
While this approach has generally proven to be satisfactory, a problem can arise when two or more calls are routed though an LEC and have the same ANI and destination 8xx. If the two such duplicate calls are in process concurrently there is no way to identify communications between the IVR and various network components as relating to one or the other of the calls. Accordingly, there is a need for a method to uniquely identify calls to an IVR, or similar system that cannot receive an NCID or out-of-band signals, where the calls have the same ANI, 8xx, and for network components to support such method.